Pathogenesis Of Congenital Heart Defects Research Articles

Role of Vascular Endothelial Growth Factor as a Potential Biomarker in Congenital Heart Defects: A Systematic Review.

Several studies have investigated the role of vascular endothelial growth factor (VEGF) variants, serum levels, and correlations with other extrinsic factors in congenital heart defects (CHDs); however, the findings need confirmation. The present systematic review evaluates the association between CHDs and genetic polymorphisms and serum expressions. Relevant literature was searched through electronic databases using keywords and MeSH terms. VEGF activity was comparatively assessed between cyanotic and acyanotic CHDs, and the association between different polymorphisms and heart defects was evaluated. We ultimately evaluated 12 studies regarding the association between VEGF serum patterns and found that serum VEGF levels were upregulated or downregulated in correlation with hypoxia and hemoglobin levels and were significantly associated with cyanotic CHDs compared with acyanotic CHDs. Our results also showed a significant role for different single-nucleotide polymorphisms, including rs699947, rs2010963, and rs3025039. The findings of the current study suggested a significant association between CHDs and VEGF genetic polymorphisms or varied serum levels. Nevertheless, more comprehensive studies may provide conclusive results and valuable insights into the pathogenesis of CHDs and relevant treatment strategies.

Functions of cilia in cardiac development and disease.

Errors in embryonic cardiac development are a leading cause of congenital heart defects (CHDs), including morphological abnormalities of the heart that are often detected after birth. In the past few decades, an emerging role for cilia in the pathogenesis of CHD has been identified, but this topic still largely remains an unexplored area. Mouse forward genetic screens and whole exome sequencing analysis of CHD patients have identified enrichment for de novo mutations in ciliary genes or non-ciliary genes, which regulate cilia-related pathways, linking cilia function to aberrant cardiac development. Key events in cardiac morphogenesis, including left-right asymmetric development of the heart, are dependent upon cilia function. Cilia dysfunction during left-right axis formation contributes to CHD as evidenced by the substantial proportion of heterotaxy patients displaying complex CHD. Cilia-transduced signaling also regulates later events during heart development such as cardiac valve formation, outflow tract septation, ventricle development, and atrioventricular septa formation. In this review, we summarize the role of motile and non-motile (primary cilia) in cardiac asymmetry establishment and later events during heart development.

Association between First Trimester Exposure to Ambient and and Congenital Heart Defects: A Population-Based Cohort Study of 1,342,198 Live Births in Canada.

The extent to which ambient air pollution contributes to the pathogenesis of congenital heart defects remains uncertain. We investigated whether first trimester exposure to ambient fine particulate matter () and nitrogen dioxide () was associated with the risk of critical and noncritical heart defects in a large population-based cohort of births. We carried out a retrospective cohort study of children conceived between 2000 and 2016 in Quebec, Canada. Heart defects were identified via data from the Maintenance and Use of Data for the Study of Hospital Clientele registry. The main exposures were average concentration of and in a) the first trimester and b) the month of conception. Exposures were estimated at the residential postal code. Associations with critical and noncritical heart defects were assessed using logistic regression models, adjusted for maternal and infant characteristics. We considered single- and two-pollutant models and assessed modifying effects of maternal comorbidity, including preexisting hypertension, preeclampsia, anemia, and diabetes. The cohort comprised 1,342,198 newborns, including 12,715 with heart defects. Exposure in the first trimester and month of conception yielded similar results; both were associated with a greater risk of heart defects. Adjusted odds ratios (OR) for any heart defect per interquartile range increase were 1.02 (95% CI: 1.00, 1.05) for and 1.10 (95% CI: 1.07, 1.13) for . Associations with atrial septal defects were 1.08 (95% CI: 1.03, 1.14) for and 1.19 (95% CI: 1.12, 1.25) for . Corresponding ORs for ventricular septal defects and individual critical heart defects were not significant. (; 95% CI: 1.06, 1.17) and (; 95% CI: 1.17, 1.31) exposure were associated with a greater risk of heart defects in mothers with comorbidity. In this population-based cohort, prenatal exposure to ambient air pollution during the first trimester was associated with an increased risk of heart defects, particularly atrial septal defects. The association with heart defects was greater in mothers with comorbidity. https://doi.org/10.1289/EHP11120.

Exposure to essential and non-essential trace elements and risks of congenital heart defects: A narrative review.

Congenital heart defects (CHDs) are congenital abnormalities involving the gross structures of the heart and large blood vessels. Environmental factors, genetic factors and their interactions may contribute to the pathogenesis of CHDs. Generally, trace elements can be classified into essential trace elements and non-essential trace elements. Essential trace elements such as copper (Cu), zinc (Zn), iron (Fe), selenium (Se), and manganese (Mn) play important roles in human biological functions such as metabolic function, oxidative stress regulation, and embryonic development. Non-essential trace elements such as cadmium (Cd), arsenic (As), lead (Pb), nickle (Ni), barium (Ba), chromium (Cr) and mercury (Hg) are harmful to health even at low concentrations. Recent studies have revealed the potential involvement of these trace elements in the pathogenesis of CHDs. In this review, we summarized current studies exploring exposure to essential and non-essential trace elements and risks of CHDs, in order to provide further insights for the pathogenesis and prevention of CHDs.

Multiple subtypes of coxsackievirus group B can cause congenital heart disease.

Different serotypes of coxsackievirus B (CVB), which is the most common cause of viral myocarditis, target cardiomyocytes through Coxsackie and Adenovirus Receptor and Decay-Accelerating Factor. Both receptors are expressed in the fetal heart. We hypothesized that infection with different serotypes of CVB during early pregnancy plays a role in pathogenesis of congenital heart defect (CHD). In this study, we use a murine model to infect with CVB1, CVB4, and combination of CVB3 + CVB4 during a critical period in gestation. We examined offspring of pregnant mice for fetal death and heart defects following viral infection. Fetuses from uninfected control dams showed normal heart development, while maternal CVB infection precipitates CHD: majorly ventricular septal defects (VSD) and non-compaction of ventricular myocardium (NC), with some infrequent cases of double outlet right ventricle, left ventricle wall rupture, right ventricle hypertrophy, and thickened/dysplastic semilunar valves. Infection of pregnant dams with CVB1 leads to 44% VSD and 41.2% NC cases, while with CVB4 leads to 31.7% VSD and 13.3% NC cases. Co-infection with CVB3 + CVB4 increases fetal pathology to 51.3% VSD and 41% NC cases. Infection can also result in fetal death, with higher incidences with CVB3 + CVB4 with 46.2% cases, compared to 33.3% by CVB1 and 21.7% by CVB4. Male fetuses were more susceptible to all phenotypes. Our report shows that prenatal CVB infections can lead to pathogenesis of certain heart defects in mouse model, particularly exacerbated with co-infections. This data confirms a link between prenatal CVB infection and CHD development and highlights it is not unique to just one serotype of CVB.

CNV Analysis Using Multiplex Ligation-Dependent Probe Amplification in Iranian Families with Non-Syndromic Congenital Heart Defects: Early Diagnosis of Non-Syndromic Patients

Background and Aims: Congenital heart defects (CHD) are the most common type of congenital disability. Copy number variations (CNVs) have been found as one of the genetic etiology of non-syndromic CHD, and researchers have detected several pathogenic CNVs in patients with cardiac defects.
 Materials and Methods: In the present study, 70 patients with familial (20 patients) and sporadic (50 patients) non-syndromic CHD were evaluated to find whether CNVs in the GATA4, NKX2-5, TBX-5, CREL, BMP4 genes, and 22q11.2 region contribute to the pathogenesis of non-syndromic CHD. We have used the Multiplex Ligation-dependent Probe Amplification (MLPA) technique as a molecular method to identify CNVs in predefined loci.
 Results: Normal MLPA results were demonstrated for GATA4, NKX2-5, TBX-5, CRELD, and BMP4 genes for all sporadic and familial cases. However, we found three patients with imbalances for the 22q11.2 region. One patient with 22q11.2 deletion showed tetralogy of fallot, and the other had ventricular septal defects/ pulmonary atresia/ multiple aortopulmonary collateral arteries. A duplication of the 22q11.2 region was detected in one patient with patent ductus arteriosus.
 Conclusion: Identifying genomic imbalances in 6% of the non-syndromic sporadic patients indicates that recurrent CNVs could be associated with non-syndromic CHD. It seems that it is the first CNV analysis using MLPA carried out in Iranian patients with cardiac defects. We suggest that 22q11.2 imbalances should be considered in patients with cardiac lesions to provide an accurate diagnosis and appropriate genetic counseling in affected families.

THE ROLE OF GENETICS IN THE UNDERSTANDING OF COMPLEX CONGENITAL HEART DISEASES

One of the most dynamic organs in the human body is the heart. Cardiac development is regulated by two key factors including signaling and transcriptional pathways. Thus, during the development of the fetus, any factor that disrupts the normal functioning of these factors may lead toward congenital heart defects (CHDs). Congenital heart disease is a complex multifactorial disease that involves both environmental and genetic factors.1,2 It is defined as any defect that occurs during heart development either in the cardiac structure or its associated vessels.3 Globally, it is one of the most common reasons for infant mortality and one of the most common birth defects in paediatric patients. As a rough estimate, 8 infants in every thousand live births are born with this fatal disease.4 Every year, in Pakistan approximately 40,000 children suffered from CHDs.5 Clinically depending upon the disease severity congenital heart diseases can be divided into two major subgroups one is non-syndromic and the other is syndromic. And among all these defects cardiac septation defects are the most common accounting for approximately 50% of the cases.6 It can be further sub-grouped as isolated lesions or complex diseases in combination with other heart defects.3 The exact mechanism involved in the pathogenesis of the congenital heart remains poorly understood but the most probable mechanism is multifactorial. Recent investigations suggest the role of epigenetic factors, micro RNA and small non-coding RNAs in the development of congenital heart defects. Moreover, advancements in molecular techniques including next-generation sequencing (NGS) helps in further detecting the genetic causes of CHDs such as the novel single nucleotide polymorphisms (SNPs) and copy number variants (CNVs).7 The current approaches used for genetic diagnosis of paediatric patients suffering from CHDs include karyotype analysis, copy number variation analysis, next-generation sequencing, and whole-genome or whole-exome sequencing. The targeted NGS relies on the selected region of know gene of interest and compared to whole genome or exome sequencing it provides us deeper gene coverage with easy variant detection at a lower cost. It provides robust detection of deletions, insertion and single nucleotide polymorphisms which chromosomal microarray analysis (CMA) and karyotyping cannot detect. To date, many pathogenic variants in different genes such as CITED2, CHD7, ZFPM2, MYH6 and KMT2D have been investigated by using targeted NGS. While whole-exome or genome sequencing help in the discovery of genes involves in the pathogenesis of congenital heart defects as it gives us more resolution at a single base-pair level. Thus accurate genetic diagnosis can be done by using the appropriate diagnostic techniques that can ultimately help in better patient counseling and clinical outcome.8 Furthermore, personalized medicines or finding mutations responsible for individual congenital heart disease patients can direct to better outcomes and approaches for each cardiac malformation phenotype. Thus, ultimately combined data of patients genotypic and phenotypic following well-designed guidelines will accelerate the translation of each SNP information into better treatment and clinical insights.9 Keywords: NGS, Single nucleotide polymorphisms, CHDs.

Estimating the frequency of causal genetic variants in foetuses with congenital heart defects: a Chinese cohort study

BackgroundThe belief that genetics plays a major role in the pathogenesis of congenital heart defects (CHD) has grown popular among clinicians. Although some studies have focused on the genetic testing of foetuses with CHD in China, the genotype–phenotype relationship has not yet been fully established, and hotspot copy number variations (CNVs) related to CHD in the Chinese population are still unclear. This cohort study aimed to assess the prevalence of chromosomal abnormalities in Chinese foetuses with different types of CHD.ResultsIn a cohort of 200 foetuses, chromosomal abnormalities were detected in 49 (24.5%) after a prenatal chromosome microarray analysis (CMA), including 23 foetuses (11.5%) with aneuploidies and 26 (13.0%) with clinically significant CNVs. The additional diagnostic yield following whole exome sequencing (WES) was 11.5% (6/52). The incidence of total chromosomal abnormality in the non-isolated CHD group (31.8%) was higher than that in the isolated CHD group (20.9%), mainly because the incidence of aneuploidy was significantly increased when CHD was combined with extracardiac structural abnormalities or soft markers. The chromosomal abnormality rate of the complex CHD group was higher than that of the simple CHD group; however, the difference was not statistically significant (31.8% vs. 23.6%, P = 0.398). The most common CNV detected in CHD foetuses was the 22q11.2 deletion, followed by deletions of 5p15.33p15.31, deletions of 15q13.2q13.3, deletions of 11q24.2q25, deletions of 17p13.3p13.2, and duplications of 17q12.ConclusionsCMA is the recommended initial examination for cases of CHD in prenatal settings, for both simple heart defects and isolated heart defects. For cases with negative CMA results, the follow-up application of WES will offer a considerable proportion of additional detection of clinical significance.

Identification of Novel Single-Nucleotide Variants With Potential of Mediating Malfunction of MicroRNA in Congenital Heart Disease.

Congenital heart defects (CHDs) represent the most common human birth defects. Our previous study indicates that the malfunction of microRNAs (miRNAs) in cardiac neural crest cells (NCCs), which contribute to the development of the heart and the connected great vessels, is likely linked to the pathogenesis of human CHDs. In this study, we attempt to further search for causative single-nucleotide variants (SNVs) from CHD patients that mediate the mis-regulating of miRNAs on their downstream target genes in the pathogenesis of CHDs. As a result, a total of 2,925 3′UTR SNVs were detected from a CHD cohort. In parallel, we profiled the expression of miRNAs in cardiac NCCs and found 201 expressed miRNAs. A combined analysis with these data further identified three 3′UTR SNVs, including NFATC1 c.*654C>T, FGFRL1 c.*414C>T, and CTNNB1 c.*729_*730insT, which result in the malfunction of miRNA-mediated gene regulation. The dysregulations were further validated experimentally. Therefore, our study indicates that miRNA-mediated gene dysregulation in cardiac NCCs could be an important etiology of congenital heart disease, which could lead to a new direction of diagnostic and therapeutic investigation on congenital heart disease.

Identification of candidate congenital heart defects biomarkers by applying a random forest approach on DNA methylation data

Background and Aims: Congenital Heart Defects (CHDs) are the most common type of birth defects, representing 0.8% of infants at birth and one of the leading causes of infant death. Although the exact etiology remains a significant challenge, epigenetic modifications, such as DNA methylation, are thought to contribute to the pathogenesis of CHDs. The present study employed a machine learning technique to analyse genome-wide methylation data in children with and without CHDs with the aim to find methylation biomarkers for CHDs.

The Interaction Analysis of SNP Variants and DNA Methylation Identifies Novel Methylated Pathogenesis Genes in Congenital Heart Diseases.

Congenital heart defect (CHD) is a rare and complicated disease with a high mortality rate. Its etiology remains unclear and includes many aspects. DNA methylation has been indicated to be involved in heart development in the early stage of life, and aberrant methylation level was related to CHDs. This study provides the first evidence of the cross talk of SNP variants and DNA methylation in clarifying CHD underlying genomic cause. We gathered whole exome sequencing (WES) data for Group 1 consisting of patients with PA (n = 78), TOF (n = 20), TAPVC (n = 78), and PDA (n = 40), and 100 healthy children as control group. Rare non-synonymous mutations and novel genes were found and highlighted. Meanwhile, we carried out the second analysis of DNA methylation data from patients with PA (n = 3), TAPVC (n = 3), TOF (n = 3), and PDA (n = 2), and five healthy controls using 850 K array in Group 2. DNA methylation was linked to WES data, and we explored an obvious overlap of hyper/hypomethylated genes. Next, we identified some candidate genes by Fisher’s exact test and Burden analysis; then, those methylated genes were figured out by the criteria of the mutation located in the CpG islands of the genome, differential methylation sites (DMS), and DNA methylation quantitative trait loci (meQTLs) in the database, respectively. Also, the interaction of differentially methylated candidate genes with known CHD pathogenetic genes was depicted in a molecular network. Taken together, our findings show that nine novel genes (ANGPTL4, VEGFA, PAX3, MUC4, HLA-DRB1, TJP2, BCR, PKD1, and HK2) in methylation level are critical to CHD and reveal a new insight into the molecular pathogenesis of CHD.

Functional evidence of mTORβ splice variant involvement in the pathogenesis of congenital heart defects.

mTOR dysregulation has been described in pathological conditions, such as cardiovascular and overgrowth disorders. Here we report on the first case of a patient with a complex congenital heart disease and an interstitial duplication in the short arm of chromosome 1, encompassing part of the mTOR gene. Our results suggest that an intragenic mTOR microduplication might play a role in the pathogenesis of non-syndromic congenital heart defects (CHDs) due to an upregulation of mTOR/Rictor and consequently an increased phosphorylation of PI3K/AKT and MEK/ERK signaling pathways in patient-derived amniocytes. This is the first report which shows a causative role of intragenic mTOR microduplication in the etiology of an isolated complex CHD.

Abstract 16811: In-Utero Coxsackievirus Type B Infection is Associated With Congenital Pulmonary Atresia

Introduction: Maternal exposure to various pathogens during pregnancy has been well established as a cause of congenital heart defects (CHD). Suggestive, although inconclusive, data exists of an association between Coxsackievirus B (CVB) infection during pregnancy and CHD. Therefore, this study was undertaken to examine association between perinatal infection with CVB and CHD. Hypothesis: CVB infection during pregnancy may play a role in the pathogenesis of CHD. Methods: In a prospective study of 122 pregnant women with pregnancies affected with CHD, circulating CVB IgG and IgM antibodies in the maternal serum were quantified. To determine specific CVB serotypes involved, Neutralizing antibodies (NA) were measured against three CVB serotypes: CVB1-Chi07, CVB3, Nancy, and CVB4, J.V.B. Results: A significant number of the women were positive for CVB antibodies; 31.1% for IgG and 6.6% for IgM. Elevated levels of IgG were seen in 50% of women carrying babies with Pulmonary Atresia (PA) (p=0.04). In addition, 55.6% (p=0.100) of moms carrying babies with Hypoplastic Left Heart Syndrome (HLHS), aortic atresia/mitral stenosis (AA/MS) variant and 47.1% (p=0.127) of HLHS AA/mitral atresia (MA) had positive IgG levels. Among babies of women with positive IgM titers, 75% (p=0.001) had isolated Ventricular Septal Defect (VSD), comprising 26.1% (6/23) of all babies with isolated VSD in the cohort.We also show a possible association between CVB4 and CHD in the cohort. All mothers with positive IgM titers whose babies were born with a VSD had elevated CVB4 NA (p=0.001). Among women with elevated IgG having babies with PA, 40.0% (p=0.061) had elevated CVB1 NA, 70.0% (p=0.014) had elevated CVB3 NA, and 40.0% (p=0.876) had elevated CVB4 NA. Conclusion: We present data from a clinical study suggesting that CVB infection during pregnancy may contribute to the burden of CHD in affected babies. Our data demonstrates not only an association of CVB with CHD in pregnant women but this is the first report showing significant association between in-utero CVB infection and PA. Our study has broad implications for the future understanding and potential management of CHD as well as introduces a new avenue of research for cardiac defects.

Element profiles in blood and teeth samples of children with congenital heart diseases in comparison with healthy ones

BackgroundSome elements were claimed to play a role in the pathogenesis of congenital heart defects (CHD) and influence the general well-being and health of these children. ObjectivesWe aimed to assess the levels of some elements simultaneously in the blood and teeth samples of children with cyanotic and acyanotic CHD compared with healthy children. MethodsA total of 39 children with CHD (11 with cyanotic and 28 with acyanotic CHD) and 42 age- and sex-adjusted controls were enrolled. Levels of 13 elements, including magnesium, phosphorus, calcium, chromium, manganese, iron, copper, zinc, strontium, cadmium, lead, mercury, and molybdenum, were assessed using inductively coupled plasma mass spectrometry. ResultsChildren with cyanotic and acyanotic CHD had significantly lower teeth calcium and calcium/phosphorus ratio as compared to the controls after adjusting for confounders. The mean blood iron level was found to be significantly higher in the cyanotic CHD group compared to the other groups. In addition, children with acyanotic CHD had significantly higher teeth copper levels, higher blood molybdenum and lower blood magnesium levels compared to the healthy control group. Blood cadmium and mercury levels were found to be significantly elevated in both the cyanotic and acyanotic CHD groups compared to the healthy control group. There were no differences in toxic metal levels of teeth in cases with CHD. ConclusionMonitoring adequate and balanced gestational micronutrient intake might support not only maternal health but also fetal cardiac development and infant well-being. Supplementation of magnesium should be evaluated in patients having CHD.

Hox-dependent coordination of mouse cardiac progenitor cell patterning and differentiation.

Perturbation of addition of second heart field (SHF) cardiac progenitor cells to the poles of the heart tube results in congenital heart defects (CHD). The transcriptional programs and upstream regulatory events operating in different subpopulations of the SHF remain unclear. Here, we profile the transcriptome and chromatin accessibility of anterior and posterior SHF sub-populations at genome-wide levels and demonstrate that Hoxb1 negatively regulates differentiation in the posterior SHF. Spatial mis-expression of Hoxb1 in the anterior SHF results in hypoplastic right ventricle. Activation of Hoxb1 in embryonic stem cells arrests cardiac differentiation, whereas Hoxb1-deficient mouse embryos display premature cardiac differentiation. Moreover, ectopic differentiation in the posterior SHF of embryos lacking both Hoxb1 and its paralog Hoxa1 results in atrioventricular septal defects. Our results show that Hoxb1 plays a key role in patterning cardiac progenitor cells that contribute to both cardiac poles and provide new insights into the pathogenesis of CHD.

A New TBX5 Loss-of-Function Mutation Contributes to Congenital Heart Defect and Atrioventricular Block.

Congenital heart defect (CHD) represents the most common birth deformity, afflicting 1% of all births worldwide, and accounts for substantial morbidity and mortality. Increasing evidence highlights the pivotal roles of genetic etiologies in the pathogenesis of CHD, and pathogenic mutations in multiple genes, including TBX5 encoding a cardiac core transcription factor key to cardiovascular morphogenesis, have been involved in CHD. However, due to pronounced genetic heterogeneity of CHD, the genetic determinants underlying CHD in most cases remain obscure. In this investigation, by sequencing analysis of the coding exons and flanking introns of the TBX5 gene in 198 unrelated patients affected with CHD, a novel heterozygous mutation, NM_000192.3: c.692C>T; p. (Pro231Leu), was identified in an index patient with familial double outlet right ventricle (DORV), ventricular septal defect (VSD), and atrioventricular block (AVB). Genetic analysis of the proband's pedigree showed that the mutation co-segregated with the diseases. The missense mutation, which altered the amino acid conserved evolutionarily, was absent from 266 unrelated healthy subjects. Functional analyses with a dual-luciferase reporter assay system unveiled that the Pro231Leu-mutant TBX5 was associated with significantly reduced transcriptional activity on its target genes MYH6 and NPPA. Furthermore, the mutation disrupted the synergistic transactivation between TBX5 and NKX2-5 as well as GATA4, two other transcription factors causally linked to CHD. This study firstly links TBX5 loss-of-function mutation to familial DORV, VSD, and AVB, which provides novel insight into the mechanism underpinning CHD and AVB, suggesting potential implications for genetic evaluation and individualized treatment of patients affected by CHD and AVB.

Using Zebrafish to Analyze the Genetic and Environmental Etiologies of Congenital Heart Defects.

Congenital heart defects (CHDs) are among the most common human birth defects. However, the etiology of a large proportion of CHDs remains undefined. Studies identifying the molecular and cellular mechanisms that underlie cardiac development have been critical to elucidating the origin of CHDs. Building upon this knowledge to understand the pathogenesis of CHDs requires examining how genetic or environmental stress changes normal cardiac development. Due to strong molecular conservation to humans and unique technical advantages, studies using zebrafish have elucidated both fundamental principles of cardiac development and have been used to create cardiac disease models. In this chapter we examine the unique toolset available to zebrafish researchers and how those tools are used to interrogate the genetic and environmental contributions to CHDs.

92: A novel epigenetic mechanism underlying maternal diabetes-suppressed mitochondrial fusion in congenital heart disease

Maternal diabetes, induces congenital heart defects (CHDs), the most common structural birth defects in human. microRNAs (miRNA) are non-coding RNAs, which represses gene expression by degrading mRNA and/or inhibiting translation. Previous studies indicate that miRNAs are potentially involved in the pathogenesis of heart defects in diabetic pregnancy. The present study investigates the role of miR-140 in maternal diabetics-induced CHDs by examining its impact on mitochondrial dynamics. Type 1 diabetes in mir140 heterozygous (miR-140+/-) female mice was induced by streptozotocin (STZ) injections. Nondiabetic miR-140+/- males mated with nondiabetic and diabetic miR-140+/-to generate hearts from embryonic day 12.5 (E12.5) and E17.5 embryos for biochemical assessment and morphological examination of CHDs, respectively. Cardiomyocytes isolated from E12.5 hearts were treated with normal (5 mM glucose) and high glucose (25 mM glucose). miR-140 expression was significantly upregulated by maternal diabetes in vivo and high glucose in vitro. miR-140 homozygous deletion significantly reduced the CHD rate from 29.1% in Wild-type (WT) embryos to 4.4% in diabetic pregnancy. miR-140 heterozygous deletion slightly reduced the CHD incidence. Maternal diabetes suppressed mitofusin 1 (Mfn1) gene expression leading to impaired mitochondrial fusion. miR-140 targeted the Mfn1 mRNA resulting in its degradation. miR-140 homozygous deletion rescued Mfn1 expression in cardiomyocytes of E12.5 hearts exposed to maternal diabetes. Mitochondrial marker Tom20 immunofluorescence staining and mitochondrial time-lapse high resolution confocal microscopy revealed that maternal diabetes induced mitochondrial fragmentation due to mitochondrial fusion impairment in embryonic cardiomyocytes. Our study demonstrates that miR-140 is critically involved in the pathogenesis of maternal diabetes-induced CHDs. miR-140 suppresses Mfn1 expression leading to impaired mitochondrial fusion. The miR-140-Mfn1-impaired mitochondrial fusion axis mediates the teratogenic effect of maternal diabetes.

Say NO to ROS: Their Roles in Embryonic Heart Development and Pathogenesis of Congenital Heart Defects in Maternal Diabetes.

Congenital heart defects (CHDs) are the most prevalent and serious birth defect, occurring in 1% of all live births. Pregestational maternal diabetes is a known risk factor for the development of CHDs, elevating the risk in the child by more than four-fold. As the prevalence of diabetes rapidly rises among women of childbearing age, there is a need to investigate the mechanisms and potential preventative strategies for these defects. In experimental animal models of pregestational diabetes induced-CHDs, upwards of 50% of offspring display congenital malformations of the heart, including septal, valvular, and outflow tract defects. Specifically, the imbalance of nitric oxide (NO) and reactive oxygen species (ROS) signaling is a major driver of the development of CHDs in offspring of mice with pregestational diabetes. NO from endothelial nitric oxide synthase (eNOS) is crucial to cardiogenesis, regulating various cellular and molecular processes. In fact, deficiency in eNOS results in CHDs and coronary artery malformation. Embryonic hearts from diabetic dams exhibit eNOS uncoupling and oxidative stress. Maternal treatment with sapropterin, a cofactor of eNOS, and antioxidants such as N-acetylcysteine, vitamin E, and glutathione as well as maternal exercise have been shown to improve eNOS function, reduce oxidative stress, and lower the incidence CHDs in the offspring of mice with pregestational diabetes. This review summarizes recent data on pregestational diabetes-induced CHDs, and offers insights into the important roles of NO and ROS in embryonic heart development and pathogenesis of CHDs in maternal diabetes.

POSTTRANSCRIPTIONAL REGULATION IN CONGENITAL HEART DISEASE: THE ROLE OF miRNA

Congenital heart disease is the most common fetal abnormality resulting in high pediatric disability and mortality. Congenital heart disease is a heterogeneous group of cardiac abnormalities including atrial septal defect, valvular defects and cardiac outflow tract anomalies. Genetic, epigenetic and ecological factors leading to the development of congenital heart defects in each particular case remain poorly understood. Nevertheless, multifactorial and polygenic mechanisms underlying the disease may be suggested. Moreover, advanced genetic technologies including single nucleotide polymorphism testing, copy number variation and next-generation sequencing ensure early detection of genetic causes of heart abnormalities. Recent studies suggested the contributing role of small non-coding RNA (miRNA) in the pathogenesis of congenital heart defects. miRNA is known to coordinate the development of heart and stimulate such pathological processes like fibrosis, hypertrophy and impaired angiogenesis. Thus, the study of miRNA and its impact on the pathogenesis of various heart diseases has demonstrated its promising potential for therapeutic targets in regenerative medicine. The review presents recent genetic findings, miRNA functions, signaling pathways and evidences on its role in the development of certain congenital heart defects.